You can consider this part of your primary app, for example if your app is lacking note taking, and you always want a small window for writing some notes, relat

You can consider this part of your primary app, for example if your app is lacking note taking, and you always want a small window for writing some notes, related to your primary app then this app always on top could be note taking. While the notes in mac can be always on top, I can think of something similar which I would always want on top.